Sendmail/Exim and IP-Address

[Roderick Ford]

Gilbert T. Gutierrez, Jr. wrote:

> The lookup name does not matter on the IP address as long as there is 
> one.  I would point the MX record to 
> "cpe-24-221-41-162.az.sprintbbd.net" not a CNAME record.
> 
> For Example:
> ecloud.org NS ns1.hn.org
> ecloud.org NS aux1.hn.org
> www.ecloud.org CNAME ecloud.org
> ecloud.org MX cpe-24-221-41-162.az.sprintbbd.net 10
> ecloud.org A 24.221.41.162
> 
> Many mail servers will not accept mail unless it has a reverse lookup 
> record associated with it.  Some mail servers will not send mail to 
> servers that are referenced by a CNAME (The reverse lookup must match 
> the MX record statement).

cpe-blah-blah.net is the reverse dns lookup for 24.221.41.162 which is 
on the router/firewall WAN side of the box.  The router forwards ports 
25/110 if I ask it to.  So what I was asking was if mail sent to 
CoolGuy@cpe-blah-blah.net goes directly to MX 10 linux.bogus.  inside 
the LAN, transparently.

By asking about aliasing that cpe- name, i was basically asking a stupid 
question.  mail sent to an "alias" that is not registered domainname of 
course will not even reach the machine.  That is one of those questions 
you might ask after midnight.

A lot of people mentioned using CNAME...which is what I was asking the 
question for.  The sendmail tutorial on sendmail.org said that you 
cannot use a CNAME, so...??  why do they say that?